Vol. 8, 1922 
PETROLOGY: H. S. WASHINGTON 
319 
3 Iridell and Minett, "Notes of the Effect of Radium in Relation to Some Pathogenic 
and Non-Pathogenic Organisms," Lancet, 1909, 1, p. 1445. 
^ Lequeux and Chrome, "Action of Radium on Bacteria," Arch. Memo. Ohst. gynec, 
3, p. 698, Dec. 1919. 
THE JADES OF MIDDLE AMERICA^ 
By Hknry S. Washington 
Geophysical Laboratory, CarnkgiE Institution of Washington 
Communicated October 4, 1922 
The following pages present some of the results of a study of jade beads, 
disks, and other small objects, found in a cenote, or sacred natural well, 
at the ancient Maya city of Chichen Itza, in northern Yucatan, the petro- 
graphic study of which was kindly entrusted to me by Prof. A. M. Tozzer 
of Harvard University. The final results will be incorporated in a forth- 
coming archaeological monograph on the contents of the cenote, under 
the editorship of Prof. Tozzer. In connection with this study, I have also 
been able to examine some ancient Mexican beads, through the kindness 
of Dr. L. Salazar, Director of the Geological Survey of Mexico, and some 
jade objects from Copan, Honduras, which were kindly placed at my dis- 
posal by Dr. Sylvanus G. Morley. I am deeply indebted to Dr. H. E. 
Merwin, of this Laboratory, for numerous optical determinations. 
There is great variety in all the characters, chemical, mineral, and phys- 
ical, of the Chichen Itza and other American jades. There are two domi- 
nant colors: green and gray. Some objects are wholly of a deep, rather 
yellowish green, like Ridgway's "pistachio green," or of a grayish green, 
like Ridgway's "pea green," the first being used for the choicest objects. 
The grays vary from almost pure white, through ash-, gull-, and dove- 
gray, to rather dark gray, most of the gray specimens being mottled in 
lighter and darker shades. Another and common type is mottled white 
(or very light gray) and a clear, bright, grass-, or emerald-green. A few 
obsidian beads were also found at Chichen Itza.^ 
The texture varies from decidedly coarse-grained, as are most of the 
pistachio-green and mottled green and white specimens, to very fine 
grained, as are most of the pea-green specimens; the gray specimens are 
mostly moderately fine-grained. The coarse-grained pieces show glisten- 
ing cleavage surfaces of pyroxene on the fracture. Nearly all these ob- 
jects have a high to very high polish, which is most marked on the coarser 
and the pistachio-green varieties. The coarse varieties are rather trans- 
lucent, as are some of the fine-grained pea-green beads; the whites and 
grays are generally opaque. 
